Results on direct CP violation in B decays in LHCb

I present three studies from the LHCb experiment on the subject of direct CP violation in $B^0$ and $B_s$ decays. First, we measure the CP asymmetry in $B^{\pm }\to \psi K^{\pm }$ decays, with $\psi =J\mathrm{/}\psi ,\psi (2S)$, using 0.35 $f{b}^{-1}$ of $pp$ collisions at $\sqrt{s}=7TeV$. We find no evidence for CP violation. Second, using the same data sample, we see the first evidence of CP violation in the decays of $B_s$ mesons to $K^{\pm }{\pi }^{-}{\pi }^{+}$ pairs, $A_{CP}(B_s\to K\pi) = 0.27 \pm 0.08 {\rm (stat)}\pm 0.02 {\rm (syst)}$($3.3\sigma$). Third, using 1.0 $f{b}^{-1}$ of data, measurements of CP sensitive observables of the $B^{\pm }\to D{K}^{\pm }$ system are presented. They include the first observation of the suppressed mode $B^{\pm }\to [{\pi }^{\pm }{K}^{\mp }{]}_D{K}^{\pm }$. Combining several $D$ final states, CP violation in $B^{\pm }\to D{K}^{\pm }$ decays is observed with a significance of $5.8\sigma$.